The invention relates to apparatus and method for running tubing into a bore of a multilateral well, including apparatus and method to run into a lateral bore not favored by gravity.
Horizontal wells are now numerous in the oil patch, driven by the benefits gained from having a larger reservoir exposure, the wells running maybe thousands of feet through the producing reservoir rather than simply passing through its top to bottom, exposing tens of feet. An extension of this technique is to drill multilateral wells where several horizontal, or at least directional, drain holes are drilled from a single surface hole. This technique can be used to gain an even greater reservoir exposure from a single surface hole, or to gain greater access to different reservoirs altogether from the same well.
Drilling multilateral wells has a cost advantage during drilling, as only a single surface hole need be drilled, cased and cemented. In cases where wellhead space is limited, such as in offshore applications, the advantages of multilateral wells are compounded further.
There is a downside, however, which can offset the potential cost savings associated with drilling of multilateral wells. Subsequent workover operations requiring re-entry into specific branches of the multilateral well can be difficult. If a simple string of tubing is run into the well, there is really no control, absent special methods and apparatus, over which branch the tubing enters. The general problem becomes one of steering a workover string into the desired branch.
There are several existing methods available which attempt to overcome the above problem. Jointed pipe rigs are known to achieve selective re-entry by putting a bend on the end of a tubing string. The tubing is run in, tracking the direction of the bend in the tubing in the process (to the extent of the accuracy possible) and directing the bend by rotating the tubing at the surface towards the best estimate of the location and direction of the desired branch. (This process can be further complicated if several junctions have to be navigated through to reach the desired final branch.) The workover tubing is run to the bottom of the particular branch it is in and the running depth correlated to the well files to determine if in fact the tubing is in the desired branch. If the tubing is not in the desired branch, the tubing is pulled back up, past the best estimate of the location of the junction, rotated again and then the whole process is repeated. This can be a time-consuming process.
Another method used is to run special jewelry in the casing at the junction points. Profiles in this jewelry allow mating diverters or whipstocks to be landed adjacent to the junction, thereby forcing any subsequent tubing or tooling run into the well into the desired branch. This method can only be used, however, if the well bore is cased at the junction. It cannot be used if it is an older well that is being re-entered to construct the new laterals, as the casing jewelry cannot typically be added after the primary casing is cemented in place. And installing the jewelry adds cost.
Coiled tubing is often a much better medium than jointed pipe for workover operations as it is quicker to use and much better suited to live well operations. An improved method and apparatus that permits coiled tubing to selectively enter different branches of a multilateral well is desirable. The bent sub method listed above cannot be used per se with coiled tubing. First, it is not possible to rotate the coiled tubing at the surface to align a bent end of the pipe to an estimated lateral. Second, there is no way of referencing which way a bent sub end is pointing by simply tracking the orientation of coiled tubing as it is run in the hole as coiled tubing, unlike jointed pipe, twists substantially downhole as it is run in a well.
Methods that attempt to address the need to run coiled tubing into selected bores using existing tooling place a rotational tool at the bottom of the coil, with a bent sub or the like beneath it. The tubing is first run in a well and enters one branch according to the chance orientation of the bent sub when the tooling reaches a junction. By tagging the bottom of the branch, the specific branch entered can be identified. If the wrong branch has been accessed, the tool is pulled back up to an estimated window location, the bent sub is rotated relative to the coiled tubing by the rotational tool, and the process repeated. Trial and error should eventually lead to the successful penetration of the desired lateral. This, however, can also be very time-consuming.
The instant invention enhances the above methodology by preferably offering a resettable element (or elements) that first detects and then leads into a lateral, the element sometimes referred to as a wand or a toe. Given the resettable option, for an initial advantage, tooling can be run in the hole through production tubing in a straight configuration, preventing possible hang-ups in the well. There is then the option of seeing which branch a tubing string naturally enters with no bend on the tooling. This could be beneficial, for instance, if a desired branch exits a main well bore from the bottom, as gravity may well take the straight tool and tubing naturally into that branch.
Further aspects of novel features of the present invention are an ability of the tool to set at least one wand or toe to sweep and detect a junction, and preferably to signal to an operator at the surface that a junction has been detected. Biasing a set wand or toe outward with an appropriate force can facilitate entering xe2x80x9cunnaturalxe2x80x9d branches, or branches not favored by gravity. Signaling the surface operator upon the detection of a junction, when put together with prior information as to the expected location of lateral branches, can enhance the efficiency of selecting a desired branch and entering it, thereby alleviating the trial and error procedure previously practiced. The methodology makes possible a progression from try and see to control and feedback.
A novel aspect of the instant invention is a remotely activatable, radially deflectable, biasable toe. In simplified terms, the deflected toe can be viewed as an adjustable or active bent sub and/or a deflectable wand. The moment of force radially deflecting the toe biases the toe outwardly, against bore hole wall portions, creating a biasing force between the toe and BHA. At least within predetermined ranges, as the lateral distance between the BHA and a bull nose portion varies, the biasing force will vary the lateral distance between the toe and the BHA.
A xe2x80x9cdetect and signalxe2x80x9d tool could also be run with electronic devices. E.g., the above tool could be run in conjunction with an electronic tool that senses the direction the tool is pointing (tool face relative to gravity or relative to north). An operator at the surface could independently infer which branch the tool is in. Other detection devices might be used that sense properties that could differentiate lateral branches. This extra tooling could remove any need to tag the bottom of a lateral to confirm the branch entered, as by instead correlating the directions of the tool or other properties with the directions or other properties of various lateral branches at a given depth. However, the basic tool may be sufficiently accurate in practice, or tagging bottom may be sufficiently inexpensive, as not to require or justify the expense of these extra electronic devices.
The inventive tool and method herein is envisioned to be able to be used in combination with all manner of coiled tubing operations, such as stimulation, logging,jetting, cleaning and perforating.
In general, while a tool to navigate into multilateral wells is not per se new, detecting lateral junctions, signaling the surface that a junction is detected, using a junction profile and/or the earth""s gravitational field to help control the actions of a tool and enhance its efficiency, to name just three points, are believed to be new.
The invention relates to apparatus and method for running tubing into a bore of a multilateral well. The method and apparatus are designed, in particular, to locate and run into an xe2x80x9cunnaturalxe2x80x9d bore of a multilateral well, e.g., a bore not favored by gravity. The apparatus and method, although not limited to, are suitable for and are particularly effective for running on coiled tubing.
The apparatus includes a bottom hole assembly (BHA) having at least one remotely activatable, radially deflectable toe. In preferred embodiments, the BHA can be said to have at least one remotely activatable, radially deflectable wand. In preferred embodiments herein, a wand carries a toe. Further, in preferred embodiments, at least one toe or at least one wand, or the combination, is laterally adjustable.
The BHA is structured in combination with at least one toe or at least one wand to produce a moment of force in a radial direction. The moment of force in the radial direction deflects at least one wand and/or toe outwardly from a bore hole longitudinal axis and eccentrically biases the toe against a bore hole wall portion, at least for a predetermined lateral range. The moment of force created in the radial direction should be of an amount at least sufficient to lift at least one toe or one wand vertically against gravity, for up to a predetermined distance. In preferred embodiments, the moment of force in the radial direction is further of an amount insufficient to lift the BHA vertically against gravity or to significantly laterally adjust the BHA.
Also, in preferred embodiments, the BHA is structured to produce a moment of force in the lateral direction, sufficient to laterally adjust at least one deflected toe or wand. Further, a port is preferably structured in combination with the BHA and the at least one wand or toe such that the port adjusts BHA fluid pressure when the wand or toe is deflected beyond a predetermined amount. In preferred embodiments, the BHA is in fluid communication through coiled tubing with the well surface, and the toe or wand and the BHA are hydraulically activated. Adjustments in fluid pressure in the BHA are preferably detectable at the surface, as a signal.
The same toe or sub may be used to detect a lateral junction and to lead a BHA and tubing into the lateral (including into an xe2x80x9cunnaturalxe2x80x9d bore hole.) However, a plurality of toes or wands might be used, with specialized functions. E.g., one or more toes or wands might be used to detect a lateral junction wherein a second toe or wand might be used to lead the BHA and tubing through the lateral junction. An economy of structure is achieved by the preferred embodiment illustrated in detail herein, using just one wand conveying one toe. It is to be understood, however, that the invention is not to be limited to the initial embodiment constructed and tested and described below.
In an alternate design, a toe or wand could be adjustable in length such that it has a first length for a detecting step and a second length for a leading step. There may be an efficiency advantage for using different lengths in different functions, and/or an adjustable length wand eliminates the need to refigure a wand length for different well bores.
The methodology for running tubing into a bore of a multilateral well includes running tubing, preferably coiled tubing, carrying a BHA into a multilateral well, radially deflecting at least one toe of the BHA to establish biased contact with a bore hole wall, moving the at least one toe in contact with bore hole wall portions and eccentrically kicking out the at least one toe. The method preferably includes sweeping, and preferably laterally adjusting, a deflected toe. In one preferred embodiment the method includes radially biasing a toe such that the toe xe2x80x9cfullyxe2x80x9d deflects only when directed toward an enlarged bore hole space located at least in part vertically above the BHA. In one preferred embodiment the method includes adjusting pressurized fluid of the BHA when a toe deflects more than a predetermined amount. In one preferred embodiment the method includes running a tool on the tubing down a well proximate an estimated lateral junction, radially deflecting at least one toe, moving the at least one toe in contact with bore hole wall portions, deflecting at least one toe beyond a predetermined amount, deflecting a wand in a radial direction assumed by a toe deflected beyond a predetermined amount, and running the tool down behind a deflected wand into a lateral bore. In the latter methodology, the toe may be carried on the wand and the step of deflecting the toe may perform the step of deflecting the wand at the same time.